The present invention relates to a hammer device, preferably a down-the-hole hammer, including a casing, a piston, a drill bit and means for activating the piston to frequently strike the drill bit. The invention also relates to a piston and a drill bit per se.
In down-the-hole hammers the kinetic energy of the piston is transmitted by elastic waves through the drill bit and finally to the rock. However, said transmission is not carried out in an optimal way since the piston is not related to the drill bit in terms of length and mass. Also the drill bit does not cooperate with the rock in the best mode.
In prior art down-the-hole hammers very little attention has been paid to the adaption of the piston to the drill bit when said drill bit has a mass concentration at the end directed towards the rock.
The aim of the present invention is to further improve the energy transmission from the piston to the rock via the drill bit. This is realized by paying attention also to the distribution of the impedance in the piston and in the drill bit of a hammer device.